​THURSDAY ISLAND, one of the smallest of the Prince of Wales group, N. of Cape York, in the Torres Strait, attached to Somerset county, Queensland, Australia. Pop. (1901), 1534. It has an excellent harbour, Port Kennedy, and is a port of call for mail steamers and the centre of the bêche-de-mer and pearl fisheries of the Torres Strait. It is a fortified coaling station for the British navy. The neighbouring Friday Island is the quarantine and leper station for Queensland.